body {
  background: #f4f4f4;
}

#loading {
  position: fixed;
  left: 0;
  right: 0;
  top: 0;
  bottom: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  background: rgba(#fff, .5);
}